Carburetor



Sept. 1, 1931. w. s. GUTHRIE GARBURETOR Filed April 9, 1923 3 Sheets-Sheet 1 .lllllll lili Il .mw

ATTORNEY.

r. w. s. GuTHmE GAHBURETOR Filed April 9, 1923 sept. 1,1931.

3 Sheets-Sheet 5 INVENTOR.

By 71V. J1 Mz;

A TTORNEY.

Patented l, 1931 UNITED STATES PATENT OFFICE WILLIAM S. GUTHRIE, F FLINT, MICHIGAN, ASSIGNOR TO' MARVEL CARBURETER COMPANY, 0F FLINT, MICHIGAN, A CORPORATION OF INDIANA CARBURET 0R Application led April 9, 1923. Serial No. 630,721.

This invention relates to the construction of carburetors for internal combustion engines, and its object is to provide a device of this character which can supply efficient and 6 economical fuel mixtures throughout a wide range of engine speeds, using either the lighter or the heavier hydrocarbons therefor.

Fuel economy at the ordinary driving speeds when the throttle is only partly open I is the prime factor in the operation of automobiles, and the purpose of the present invention is to provide a carburetor which will accomplish this purpose. The present invention provides novel means for automatically :varying the opening of an auxiliary fuel passageway so that the supply of fuel delivered to the engine will be varied according to its requirements, which means are so constructedthat the several Vparts will not readily Vget out of adjustmentl because of wear. The several moving parts of the carburetor are concealed within the body thereof and are therefore protected from dust. The kmoving parts are lubricated by the fuel which tends to prevent wear and to lengthen the life of the moving parts.

This invention also provides novel means for augmenting theI normal fuel supply, when the engine is tobe accelerated, in the form of an auxiliary reservoir from which the fuel used when the engine is idling is or may be obtained, the level of the fuel in this auxiliary reservoir when the engine is idling being raised considerably above that of the fuel in the main float chamber of the carburetor, and this fuel in the auxiliary reservoir forcing itself to the main fuel nozzlel of thecarburetor, which is at a lowerf `,so that 'fuel is thereby supplied only when the air pressure in said .suction passage is lower than the air pressure therein below the throttle. This feature of the invention tends to prevent the mixture becoming slow burning and therefore eliminates, very materially, the usual explosions in the mulier when driving the automobile at relatively high speeds and suddenly closing the throttle for regulating the movement ofl the throttlevalve. Fig. 3 is a section on the line 3-3 of Fig. 2. Fig. 4 is a section on the line 4 4 of Fig. 1. Fi '5 shows a part sectional view of a modi ed form of fuel valve. Fig. 6 shows a push rod for opening the auxiliary fuel valve. Figs. 7 and 8 show modified forms of carburetors in sections similar to Fig. 2 showing the usual stopper arm on the throttle arm for regulating the movement of the throttle valve. Figs. 9 and 10 are views of modified formsV of carburetors in partial sections similar to Fig. 1. Figs. 11 and 12 show sections of the throttle shafts shown in Figs. 7 and 8. Fig. 13 is a part sectional View on line 141-14 of Fig. 1. Fig. 14.- is a sectional view on line 15-15 of Fig. 13. Fig. 15 is a sectional view on line 16-16 of Fig. 13. Fig. 16 shows a sectional view of a modified form of nozzle. Fig. 17 shows a top view of the nozzle. Fig. I8 shows a modification of the nozzle.

Similar reference numerals refer to like pearts throughout the several views.

Referring to `Figs. 1, 2, 3,4, 6, 13, 14 and 15, 'the body 1 of the carburetorv has a fuel mixture outlet 2 at its upper end and an air inlet elbow 3 at its lower end. Within the body 1 and just above the carbureting chamber 4 is a throttle valve 5 on a horizontal shaft 6 adapted to be turned by the control lever 7.

The venturi 8 within the body 1 is between the air inlet 3 and the carbureting chamber 4. A constant level liquid fuel supply chamber 9, or float chamber, is shown integral with the body andpis provided with a float 10 to control the fiow of the fuel to the float chamber in the usual manner.

A fuel passage 11 connects the fuel nozzle 12 with the auxiliary reservoir 13 and with the fioat chamber 9. A removable bushing 14 has an orifice, 15 into which extends the tip of the needle yalve 16 which controls the flow of the fuel from the float chamber 9 to the fuel passage' 11. A calibrated orifice 15 renders the needle valve unnecessary, as is the case in the structure shown by Figs. 9 and 10.

An auxiliary chamber 17 receives fuel from the auxiliary reservior 13 by means of the tube 45a having an orifice 80 near its lower end, and receives air through the orifice 19 whichmay be drilled in the body when desired. The orifices 20 and 21 connect the chamber 17 with the mixture outlet 2 of the carburetor, the area of the orifice 20 being controlled by the needle valve ,22. The tube 45a is secured to the plug 45', so that when the plug is removed the tube is also removed. The orifice 21 is restricted, or calibrated, so that it supplies the proper f liel when the adjacent edge of the throttle is slightly below it.

The fuel nozzle 12 is provided with a removable bushing 24 having a calibrated orifice, and this bushing may be held in position by means of screw threads at 25.

The throttle shaft 6' is cut away to form a cam at 26 (Fig. 2). A coiled spring 27 located in the chamber 28 parallel to the nozzle 12 tends to hold the valve 29 up against its seat at 30. The lower end of the coiled spring 27 is supported by the bushing 31, the latter being held in position by means of screw threads at 32.

The chamber 33 below the bushing 31 is connected with the fuel conduit 11 by the passage 34.

The annular space 36 around the reduced portion of the valve 29 is connected with the float chamber 9 by the fuel passage 37 (Fig.

4). A push rod 38 is positioned between the valve 29 and the cam 26 so that the cam may engage this rod to .push down the valve 29.

The calibrated orifice of the bushing 31 permits fuel to fiow from the chamber 28 to the chamber 33. The orifice 35 may be controlled by a needle valve when desired, as for example, a valve similar to the valvel 16 incontrol of the orice 15.

The annular space 39 formed by the reduc-l tion in size of the push rod 38 connects to the atmosphere by the opening 40 which prevents the suction that may be caused by leakage around the upper end of the rod- 38, from infiuencing the fuel in the chamber 36.

The push rod 38 and the valve 29 may be made of one piece, as shown in Figs. 7 and 8, when desired. A valve 41 (Fig. 5) having a' by-pas's around its seat, formed by drilling at 42, 43 and 44, may be usedV in place of the valve 29 when desired. By using the valve 41 having a calibrated orifice 43, the needle valve 16 and bushing 14 may be eliminated. The passage 42 may be calibrated to supply the constant supply of fuel in place of the orifice 15.

The orifice 87 opening into the mixture outlet or suction passage 2 above the throttle has communication with the auxiliary reservoir 13 at 88. A vertical passageway 89,

(Figs. 14 and 15) connects the orifice 87 with the orifice 88. The orifice 88 is preferably calibrated and while it is shown in the bushing 90, it may be drilled in the body when desired. The passageway 89 receives air through the calibrated orifice 91 in the bushing 92. When desired to receive the air at a higher level, the bushing 92 may be placed at 93 and theplug 93'may be used to close the lower opening. The usual sleeve and choke valve, not shown, may be attached to the intake 3 for use in starting the engine.

The operation of the carburetor is as follows.

Assuming that thefioat chamber 9 'is properly supplied with fuel, and that the engine is idling with the valve 5 between the orifices 20 and 21, the reservoir 13 is filled with fuel up to the level of fuel in the float bowl. The suction created in the chamber 17 influences the fuel to rise up the tube a and with air from the orifice 19 this fuel passes out into the mixture outlet 2 through the orifice 20. The mixture supplied through the orifice 20 is too rich for combustion, but theair passing the partly open throttle properly dilutes the same for idling the engine. The valve 22 may be employed to regulate the flow of the fuel through the orifice 20. When the throttle 5 is opened to a greater degree for slightly higher speed, the orifice 21 'will discharge the rich mixture from the'passage .17 'in addition to that discharging from the orifice 20'.'

When the throttle is opened to a still greatl' er degree, the suctionat the upper end of the nozzle 12 will cause the fuel to discharge therefrom into the chamber 4.l The air from the intake 3 flowing up through the venturi 8 mixes with and conveys the fuel to the,en

gine through the suction passage 2 in the .usual manner.

When the throttle is opened sufficiently to materially reduce the suction in the passage 2 above the valve, it will cause the level of the fuel in the reservoir 13 to lower andthe fuel to be discharged by the orifice 24 in the nozzle 12. A quick opening of the throttle from the idling position will cause the fuel in the reservior 13 to drop rapidly by reason of its weight and height, which tends to force this fuel from the orifice 24 in addition to the suction infiuence on the fuel in the nozzle 12.A The passageway between the reser voir 13 and the nozzle 12 is preferably freely l fices 86 and 92.

The orifice 86 maybe used to admit air to the reservoir 13 when required to obtain desired results, and it may be positioned in a removable bushing when desired.

When using the carburetor on an automobile, the needle valve 16 should be regulated to limit the fuel supply flowing through the orifice 15 to ive the maximum fuel necessary when drivlng at a steady speed at 20A or 25 miles per hour. l

The size of the calibrated orifice 24 is such that it is capable of a much greater discharge than is supplied by the above adjustment of the valve 16 at the above speed, so that inasmuch as the reservoir 13 is connected with the passage 11 and nozzle 12, air will pass from the reservoir 13 to the orifice 24, which air i's obtained through the orifices 86 and 92. With the above adjustment the automobile will travel up to about forty miles per hour on good roads without its engine indicating leann'ess of mixture, and just before the mixture begins to show leanness, the'cam 26 begins to function for it is so positioned in relation to the throttle 5l that it beginsio force the valve 29 open to augment the fuel supply for the hig er speeds through use of the passage 37. f

The orifice 35 is calibrated to vlimit the flow of fuel to give the maximum power of the engine, or the maximum speed of the automobile.

The size of the orifice 24 should be as large as possible without causing undue loading when running with wide open throttle at slow speeds. The lower end of the valve 29 is slotted so that a screw driver may be used to grind the valve to its seat. The position of the cam 26 in respect to the throttle 5 is preferably such that the valve 29 is open when the engine is idling, as shown in Fig. 3.

When the valve 16 is adjusted to supply/a lean mixture, as above set forth, it is very likely to cause too l'ean a mixture for good performance at slow speeds, especially when the `throttle is frequently closed and opened, which occurs when driving an automobile in heavy traffic. This undesirable performance is caused by the fuell flowing too slowly rthrough the orifice 15 when decreasing the speed of the engine and must be compensated for by supplying additional fuel.

After driving the automobile at a speed of about forty miles per hour and suddenly permitting the throttle to close, theair pressure in the suction passage beyond the throttle is reduced to such'a material extent that the orifice 20 would be forced to deliver all the fuel flowing through the orifice 15 if it were not for the auxiliary supply. This, of course. would cause the nozzle 12 to empty and remain so until the suction in the suction passage regains normalcy.

Should the throttle be opened slowly before the suction has become normal for the idle position of the throttle, it may cause a back fire in the carburetor or a jerk in the car, which is due to lack of fuel in the nozzle 12 at that time.

When the cam 26 is arranged as above described, so that the auxiliary fuel passage is open when the throttle is in the idling position, it is obvious that the additional fuel will keep the nozzle 12 filled under the abnormal condition above described, and thus assure good performance and maintain economical mixtures for driving the automobile under normal conditions.

The cam 26 should not hold the valve open for a speed to exceed about fifteen miles per hour, because the orifice 24 thereafter feeds fuel quite freely, if it can get it, and to bc economical, it must not -get the auxiliary fuel supply when driving the car under normal conditions at speeds from fifteen up to about forty miles per hour.

When the throttle valve 5 is suddenly closed, as above stated, after driving at relatively high speeds, the level of the fuel in the auxiliary reservoir 13 will rise still higher, and, flowing through the orifice 88 and passing up the vertical passage 89 with air from the orifice 91, discharges into the mixture outlet 2 through the orifice 87. The fuel thus flowing from the reservoir 13 augments the supply discharging from the orifice 2O and thereby prevents explosions in the muffler, usually occasioned in this type of carburetor by the mixture being too lean for this abnormal condition.

In Fig. 7, the flow of the fuel from the chamber 36 is controlled by the valve 46, which valve has a piston-like end 47., A suction chamber 48 is at the upper end of the valve piston 47. A chamber 49 communicates with the suction passage 2 above the valveY 5 by means of a restricted orifice 50. The calibrated orifice 55 admits air to regulate the pressure in the chamber 49 so that when the throttle is closed a predetermined degree, the suction will lift the valve 46 to its seat. The passage 51, drilled through the throttle shaft 6a, (F1g. 11)., permits the chambers 48 and 49 and the extensions52 and 53 thereof to communicate. Two grooves 54 are located in the shaft 6a, one to register with the passage 53 when the throttle is wide open and the other when the throttle is closed to idle thc engine. These ventsprevent suction caused by leakage from influencing lthe valve 46 to rise when the auxiliary fuel is desired. A plug 56 has a stem extended within the path of the valve 46 so as to hold the valve reasonably near its seat, when open.

Fig. 8 shows an auxiliary nozzle 57 which has a restricted orifice 58. The passage 59 connects the nozzlel 57 with the chamber 33 so that the auxilia fuel is dischar ed only by the orifice 58. T e calibrated ori ce in the lower end of the valve 46 permits a very limited amount of fuel to flow uncontrolled by the valve 46. The nozzle 57 is therefore kept filled with fuel at all times, and when the nozzle 12 is emptied by such abnormal conditions as above described, the orifice 58 will -discharge fuel and thereby avoid the undesirable operations above set forth. The orifice 58 is calibrated to limit the flow of fuel for high speeds.

A bushing 62 positioned around the throt tle shaft 6b has a circumferential groove 63 forming an annular assage to secure constant communication etween the chambers 48 and 49 (see Fig. 12). The orifice 50 is controlled by the valve 64 so. as to regulate the pressure 1n the chamber 48 to cause the valve 46 to open when additional fuel to secure maximumspeed is desired. The valv 64 may be substituted by a calibrated orifice like that shown in Fig. 7 at 55, when desired, or vice versa.

- In Fig. 9'the chamber 71 above the auxiliary reservoir 13b is o en to the outside atmosphere by means o an orifice drilled through the screw 71a. Fuel from the reservoir 13b flows up the tube 73 and is discharged into the chamber 71 through the calibrated orifice 74 for idling the engine. The air flowing in through the orifice 72 permits the fuel in the reservoir 13b to flow out through the nozzle 12 during high engine sieeds. The orifice a near the u per end o the tube 73 vente the tube and al ows the fuel to rise in the tubes 73 as before described. The tube 73 is secured to the bushing 75, the latter being removable as it is held 1n place by screwthreads.

In Fig. 10 the tube 78a extends down to tno lower part of the reservoir 130. The fuel flows u the tube and dischar es through the orifice the mixture outlet passage 2 through the orifice 20. The orifice 76 may be located in a removable bushing similar to the bushing 19 shown in Fig. 1 and for the same purpose when desired. i

A series of rts 99 horizontally arranged in the wall ofxtbe .nozzle 12 (Fig. 1) at its lower end distributes the air flowing from the reservoir 13 into the fuel -as it flows' up the vertical passageway within this nozzle.` The air flowing from the reservoir 13 passes through the fuel passage 11 above the top of the fuel therein and this air naturally prefers to pass through the ports 99 rather than force its way downwardly to the bottom of the nozzle 12. This construction has -been found to materially increase the ellicienc of the carburetor when used on an engine that was especially diliicult to handle. An increase in .ordinarily the case.

7 into the chamber 1 and with air owing through the orifice 76 passes out into power with considerably less fuel was brought about by substituting this nozzle for one similar to that shown in Fig. 9 of the drawings. Some engines, however, may be carbureted with the imperforate type of nozzle. Too much air flowing to the passage 11 will cause the mixture to become lean at speeds below forty miles per hour and this necessitates having the auxiliary fuel valve 21open, which leaner mixture is objectiona e.

The enlarged nozzle 94 shown, in Figs. 16 and 17 is especially desirable to use with some special engines considered hard to carburete. Air from the air intake of the carburetor enters the ports 95 and passes up the annular passage 96 out into the mixing chamber with fuel from the orifice 97. The fuel and air thus discharging are mixed t0 some extent at 98 before discharging into the main air passageway. The several ports 99 at Ythe lower end of the nozzle 94 permit the air flow ing through the fuel passage 11to be distributed through the fuel flowing up the nozzle, and tends to mixy more thoroughly than is Fig. 19 shows the lower end of the nozzle made without the ports 99, and it may be used this way when desired.

The several features of the invention are of lectively, according to the engine requirement, and it is intended that only one or more of them may be used as may be desired.

The restricted orifice 90 ('Fig..14) is pre. ferred because it permits the use of la'rger orifices 87 and'91' than otherwise in orderto prevent too much air flowing to the reservoir 13 from this source, but I may sometimes have this connection unrestricted and have the orifices 87 and 91 so proportioned as to permit the proper amount of air.

Other types of carburetors may be iniproved by incorporating one or more of the featuresof my invention as above set forth and such combinations as are setforth in the claims. Various Acombinations of the parts and ideas shown and` described may be madey other than as shown without departing from the scope of my invention.

ysuch nature as may be used separately or col ioo 1. In a carburetor, a body having a mixing chamber therein and a fuel passage terminating in a vertically disposed fuel nozzle normally supplying fuel to said mixing chamf` ber, means for supplyingfuel and air to said fuel passage, said nozzle having horizontal air ports in the wall thereof adjacent the point of entrance of fuel to ysaid nozzle withf mixing chamber therein and-a fuel passage 130.

bowl to horizontal passage end, means for terminating in a vertically disposed fuel nozzle normally supplying fuel tosaid mixing chamber, means for supplying fuel and air to said fuel passage, said nozzle having a depending end extending into said fuel passage provided with horizontal air ports in the Wall thereof adapted to distribute said air supply to the fuel while the latter flows through said nozzle, an auxiliary fuel supply and means controlled by the throttle valve for automatically supplying fuel to said fuel nozzle when the throttle valve is in position for the engine to id e and for high speeds of the engine.

3. In a carburetor having a body with a mixing chamber therein, a horizontally arranged passage through which fuel and air normally flow, a vertically disposed nozzle having a depending end extending into said and having air ports adjacent its said llower end adapted to supply air to the fuel passing through said nozzle.

y4. A carburetor comprising a body having a mixing chamber and a fuel passage, a vertically disposed fuel-nozzle at the end of said passage for supplying fuel to said mixing chamber at high engine speed, said nozzle extending into` saidY fuel passage and having a series of air openings adjacent its lower suppl ing fuel and air to said fuel passage w iereby fuel passing through said nozzle will be supplied with air from said air ports at the point of entrance of fuel to said nozzle.

5. A carburetor for internal combustion engines comprising a body having a mixing chamber provided with 'an air inlet, a throttle shaft extending. throughl the walls of said mixing chamber provided with a throttle valve, a fuel nozzle extendin into saidl mix` ing chamber, a fuel bowl, a uel passage extending from said bowl to said nozzle, an auxiliary fuel passage extending from said said nozzle, a valve for controlling the passage of fuel through said auxiliary passage, said body having a vertical bore in one wall thereof, a rod slidably mounted in I said bore operated by the throttle shaft for opening said valve to allow fuel to pass through said auxiliary fuel passa e when the throttle valve is in substantie ly open position and substantially closed position.

WILLIAM S. GUTHRIE. 

